Treating Resistant Rocky Mountain Species By Regular and Modified Double-Diffusion Methods

Engelmann spruce, lodgepole pine, and Rocky Mountain Douglas-fir posts were treated as follows: A): 1 day in CuSO4 1 day in NaHAs04-Na2CrO4; B) 3 days in CuSO4 3 days in Na2HAs04-Na2CrO4); C) 8 hours in CuSO4 (solution hot — 200?F) 1 day in cold Na2HAs04 -NaCrO4. D) (Posts incised) – 1 day in CuSO4 day in Na2HAs04-Na2Cr04. Engelmann spruce and lodgepole can meet retention requirements of 0.40 pcf of chromated copper arsenate (based on the oxides Cr03, CuO, and As205). All variations of the treatment met this requirement except the 1-day plus 1-day treatment with unincised posts. The only treatment which met the retention requirement for Douglas-fir was the 1-day plus 1-day or incised posts. This treatment also introduced the most salts into Engelmann spruce and lodgepole pine. The average minimum penetration in Engelmann spruce was greater than 3/4 inch for all treatments except treatment A or, the 1-day plus 1-day with unincised posts. For lodgepole pine, average minimum penetration was greater than 3/4 inch for all treatments except the 1-day plus 1-day with unincised posts and the 3-day plus 3-day. Also, these, two methods did not penetrate all of the sapwood while the other two did for lodgepole pine. The average minimum penetration of Douglas-fir was less than 3/4 inch for all treatments. Douglas-fir had complete sapwood penetration with all treatments, but no heartwood penetration.

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